• sqoop从mysql导入到hdfs出现乱码问题


    最近把hive元数据库的快照数据导入到hdfs中,以便对历史的元数据进行查询。
    命令如下:

    sqoop import -D mapred.job.queue.name=do.production --connect 'jdbc:mysql://qqq:3306/hive?defaultFetchSize=1000&useUnicode=true&characterEncoding=UTF-8&characterSetResults=utf8&characterSetConnection=utf8&characterSetClient=utf8' --username aaa --password bbb --target-dir hdfs://xxxxxx/hive/warehouse/hive_metadata.db/nucleus_tables/daykey=20171024/1508813696533_22e17035-894f-41e4-869c-fb154673da9e --null-string '\N' --split-by CLASS_NAME --hive-drop-import-delims --delete-target-dir --hive-overwrite --null-non-string '\N' --lines-terminated-by "
    " --fields-terminated-by '01' --query 'select *, 20171024 from hive.NUCLEUS_TABLES where $CONDITIONS' 
    

    但是导入过程中出现了错误:

    Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'org.apache.hadoop.hive.metastore.model.MQ����n��' )' at line 1
    

    sqoop会按照split-by的字段组成这个sql,然后用这个区间的CLASS_NAME做切分,给mapreduce执行:

    SELECT MIN(CLASS_NAME), MAX(CLASS_NAME) FROM (select *, 20171024 from hive.NUCLEUS_TABLES where  (1 = 1) ) AS t1
    

    看到乱码问题,直接在mysql连接串中加上:useUnicode=true&characterEncoding=UTF-8,但还是不行

    试了一个早上,发现NUCLEUS_TABLES表都是varchar字段,而且长度还是蛮长的,心想是不是split-by不支持varchar字段还是要求有长度限制呢?
    于是改了一下执行命令

    在split-by中加上截取字符串的函数:

    sqoop import -D mapred.job.queue.name=do.production --connect 'jdbc:mysql://qqq:3306/hive?defaultFetchSize=1000&useUnicode=true&characterEncoding=UTF-8&characterSetResults=utf8&characterSetConnection=utf8&characterSetClient=utf8' --username aaa --password bbb --target-dir hdfs://xxxxxx/hive/warehouse/hive_metadata.db/nucleus_tables/daykey=20171024/1508813696533_22e17035-894f-41e4-869c-fb154673da9e --null-string '\N' --split-by 'substring(CLASS_NAME, 40, 1)' --hive-drop-import-delims --delete-target-dir --hive-overwrite --null-non-string '\N' --lines-terminated-by "
    " --fields-terminated-by '01' --query 'select *, 20171024 from hive.NUCLEUS_TABLES where $CONDITIONS' 
    

    于是成功了~
    上面出错的org.apache.hadoop.hive.metastore.model.MQ到最后的Q就已经出错了,在mysql中找不到记录,数了一下前面的字符,到M有正好有40个。怀疑split-by一个字段有40个长度的限制,否则有问题

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  • 原文地址:https://www.cnblogs.com/lanhj/p/7723233.html
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